Along with the spread of mobile devices such as cell phones in recent years, in order to extend usage time of the mobile devices, the need for reducing power consumption for implemented application processors is increasing. In order to realize this reduction in power consumption, there is a need for a power supply control circuit that can be activated at high speed and in which high accuracy suppression of output voltage variation is possible. With regard to a high accuracy power supply control circuit, in a case where it is attempted to realize high accuracy control that suppresses the output voltage variation by PID control or load variation, since computational expressions related to control are complicated and the number of computations increases, implementation by a conventional analog circuit is difficult, and implementation is done by a digital circuit.
For example, Patent Document 1 discloses a digital control system power supply device having a transformer, a switching means for switching application of electrical power to a primary (coil) winding of the transformer in accordance with the duty of a received pulse width modulation (PWM) signal, a detection means for detecting an output value for a load connected to a secondary (coil) winding side of the transformer, a sampling means for sampling the output value detected by the detection means, an averaging means for averaging the sampled output value and outputting an average output value, and a duty determination means for determining duty corresponding to a target value based on the average output value outputted from the averaging means. According to this type of digital control system power supply device, it is possible to supply a stabilized output to a load.    [Patent Document 1] JP Patent Kokai Publication No. JP-P2005-185045A